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List:       comedi
Subject:    Re: [NI PCI-6071E] AI Start Trig
From:       Martyn Welch <welchm () comp ! lancs ! ac ! uk>
Date:       2005-07-29 9:00:02
Message-ID: 200507291000.05609.welchm () comp ! lancs ! ac ! uk
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- ------ Original message ------
On Tuesday 26 Jul 2005 20:13, David Schleef wrote:

> On Tue, Jul 26, 2005 at 05:40:09PM +0100, Martyn Welch wrote:
> > From the documentation I have I believe this to be the "PFI 0/AI START
> > TRIG" signal. This line doesn't seem to be outputting anything, I guess it
> > is setup as input by default.
>
> Correct.
>

Is that "correct" as in "it's set up as input by default" or "the AI START 
TRIG line is triggered when a command-type capture is started" or both?

> > How can I set the line up as output?
>
> The PFI lines are available as subdevice 7.  You simply need to
> configure the correct line for output.
>

I think I have done this, though it doesn't seem to be working...

I've attached an example I have written.

Thanks for your help,

Martyn

- -- 
Martyn Welch (welchm@comp.lancs.ac.uk)

PGP Key : http://ubicomp.lancs.ac.uk/~martyn/pgpkey/
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["main.c" (text/x-csrc)]

/* Created by Anjuta version 1.2.2 */
/*	This file will not be overwritten */

#include <stdio.h>
#include <comedilib.h>
#include <string.h>
#include <unistd.h>

//Sub-Devices to use
#define AI	0
#define AO	1
#define DIO	2
#define PFI	7

//Define number of conversions to make
#define N_SCAN 10

//Define number of channels to scan
#define N_CHAN 2

//Function to create capture command list
int setup_input(comedi_t *, comedi_cmd *, char, char);

int main(){

	comedi_t *it;					// Global for DAQ card pointer
	unsigned int i;					// Loop Var
	comedi_cmd cmd;					// Command List
	unsigned int chanlist[N_CHAN];	// Channel List
	unsigned int buf_len = N_SCAN * N_CHAN;
	char buf[buf_len];
	int ret;
	long scan_num = 0;
	
	//Open DAQ Card
	it = comedi_open("/dev/comedi0");
	if(it == NULL){
		comedi_perror("comedi_open");
		return(1);
	}
	
	//Setup PFI Channels
	for(i=0;i<10;i++){
		if(comedi_dio_config(it, 7, i, COMEDI_OUTPUT) != 1){
			comedi_perror("comedi_dio_config(PFI)");
			return(1);
		}
	}
	
	// Set up channel list
	for(i=0;i<N_CHAN;i++){
		chanlist[i]=CR_PACK(i,0,AREF_GROUND);
	}

	// Clear cmd memory
	memset(&cmd,0,sizeof(cmd));

	// This comedilib function will get us a generic timed
	// command for a particular board.  If it returns -1,
	// that's bad.
	if(comedi_get_cmd_generic_timed(it,AI,&cmd,800) < 0){
		comedi_perror("comedi_get_cmd_generic_timed");
		return 1;
	}

	// Modify parts of the command
	cmd.chanlist		= chanlist;
	cmd.chanlist_len	= N_CHAN;
	cmd.scan_end_arg 	= N_CHAN;
	cmd.scan_begin_arg = 4000;
	cmd.stop_arg = N_SCAN;
	
	// comedi_command_test() tests a command to see if the
	// trigger sources and arguments are valid for the subdevice.
	//Print Error and user check if command needed changing...
	if(comedi_command_test(it,&cmd) != 0){
		fprintf(stderr,"Command Needed Changing\n");
		return(1);
	}

	//Run Command
	if(comedi_command(it,&cmd) < 0){
		comedi_perror("comedi_command");
		return(1);
	}
	
	while(1){
		ret = read(comedi_fileno(it),buf,buf_len);
		if(ret<0){
			// some error occurred 
			perror("read");
			break;
		}else if(ret==0){
			// reached stop condition
			break;
		}else{
			static int col = 0;
			for(i=0;i<ret/2;i++){
				
				printf("sensor:%d\ttime:%luns\tvalue:%lu\n", col, (unsigned long)((scan_num * \
4000) + (col *800)), (unsigned long)(((sampl_t *)buf)[i]));  
				col++;
				if(col==N_CHAN){
					col=0;
					scan_num++;
				}else{
				}
			}
		}
	}

	return(0);

}


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